Process for treating oil



U. B.,BRAY

PROCESS FR TREATING OIL Filed July '7, 1930 `.Patented Oct. 22, 1940 N PATENT .oFFIcE `2,218,515` rRooEss FOR TREATING oIL Ulric B. Bray, Palos Verdes Estates, Calif., as"

Signorto Union Oil Companyof California, Los Angeles, Calif., a corporation of CaliforniaJ v Application July 7, 1930, seria11-10.466,190

17 claims. Y(c1. 19a-1s) 1n the co-pending application Serial No.

466,189 is described a process for the extraction of asphaltic materials from oil containing lubricating fractions under conditions such as to preservetthe inherent characteristics of the lubricating oil.

Subject matter disclosed herein but not claimed is claimedin the following copending application and patents: Serial No. 466,189, claiming dewaxing with a liquefied normally gaseous hydrocarbon; Serial No. l 597,419, filed March '7, 1932,

claiming deasphalting with distillation; Serial No.`705,910, filed January 9, 1934, a division of Serial No. 466,189, claimingwax separation under controlled pressures, centrifuging, u Y alternate chilling and` special features of construction; 4

SeralNo. 707,641, filed January` 22,` 1934, claimingseparation of asphalt or kindred material in conjunction with heating; Serial=Nos. 721,602, `lecl April20, 1934 and .749,649 filed October 23, 1934, both divisions of Serial No. 466,189 and claiming treatment with `butane; Patent No. 1,944,491 claiming .separation of 3 `asphalt and wax; Patent No. 1,949,989, claiming' asphalt septreatment in conjunction with the use of heavier solvent materials. i I

. Distillation of oil in the presence ,of asphalt induces in the oil a chemical and perhaps physi-` cal.` transformation which .destroys 'in `it bodies or` propertieswhich impart to the oil a relatively u small change of viscosity with change in temperature.` `In order to preserve thesecharactery istics without any change it was found necessary never to heat the oil above those temperatures `necessary. to remove oil having a Viscosity of 400500lseconds Saybolt Universal at 100 F. If

620 F. the distillates produced have their viscosity-temperature characteristics impaired. Lubricating oils were therefore produced by removing 'thelight fractions from crude'oil up to those fractions having a viscosity of 400-500 f seconds` Saybolt Universal at 100 F. The distillation 'was carried out with sufficient steam to maintain" the temperature below `that at which f the asphalt induces the deleterious transforma-v tions in the viscosity temperature characteristics ofthe\oil,"i. e., below 60G-630? F. The oil is then` extracted with solvents which are capable of :dissolving the lubricating oil but notof dissolving the asphalt. Such solvents are naphtha, `gcaslnghead 1 gasoline, liquid hydrocarbon gases aration; Patent No. 2,006,098, claiming chemical. treatment .in conjunction with propane treat-V ment; andLPatent No. 2,031,204, claiming propane the oil is heated in the neighborhood of600 to' such` as propane and `butane and` mixtures of propane and butane, ether and alcohol, and mix. tures, of ether and alcohol, and acetone.

I prefer to use liqueed propane and butane to extract the oil from asphalt by mixing the solvent and the oil under pressure. This liquid solvent is obtained in the rectication of natural gas gasoline anda typical analysis of such a solvent is 6.72% ethane, 721.20% propane,` 19.91% isobutane and 1.17% normalbutane; The asphalt precipitates out and is allowed to settle under pressure. The mixture of lubricating oil and solvent is then withdrawn from thepressure separator by flashing it `through. a heating coil into a separator where the vaporized propane` and butane are Withdrawn from the lubricating oil. The vaporized solvent is recondensed by the use of pressure and is cooled and returned to the process.

- produced from the selected crude in any desired manner, is taken from the topped residuum storage tank l through line 2 to the suction of pump 3 to ,be'sent through the T ll into mixing coil 5, and is discharged intof decanter 6. Thepressure in 6, lllfand 4l is controlled and equalized by connecting lines and is maintained at about pounds which at ordinary temperatures will maintain the solvent in liquid condition. At T 4 a stream o f liqueed propane containing a small amount of dissolved lubricating oil, coming through line I8, 'is mixed with the topped residuum. The liquid propane and topped residuum are thoroughly mixed in passing through mixing coil 5 discharging into decanter 6.` The asphalt in the topped residuum is` precipitated by `theliquid propane in .the form of -a j slurry, which settles to the bottom of decanter 6. The asphalt slurry from the bottom of dectaner 6 is 'sent by pump l through line 8 to T 8 where it is mixed with fresh liquid propane coming from propane storage 4l `through line 56 to pump 51 and thence throughline 58 to T 8. The mixture is passed through mixing coil 9 for complete mixing and' then into decanter l0. The

asphalt slurry` from the bottom of decanter I0 is drawn' off through the pressure reduction valve tion passing pressure reduction valve 2I r pressor 54.

I I and sent through line II to coil I2 in furnace I2 Where suflicient heat is applied to effect vaporization of the propane and the melting of the asphalt. The heated material from coil I 2 passes through line I3 into evaporator I4, into which steam is introduced via I4 to aid in ashing the last of the propane, and reducing the asphalt to satisfactory flash and fire specifications. The reduced asphalt from evaporator I4 is drawn off through line I5 and sent .to asphalt storage tank I3. The overhead from evaporator I4 is sent through line 50 to condenser 5I and into separator 52. The uncondensed propane from separator 52 is sent through line 53 to propane corn- Water is removed through line 52 and condensed light lubricating oil through 52". The compressed propane is sent through line 55, T 44, and line 45 to cooler 46 where the propane is liquefied, and passes into propane storage41. The overflow from decanter I0 consisting of a propane solution of lubricating oil passes through pump I1 and line I 8 to T 4, where it is mixed with the incoming topped residuum as described above. The overflow from decanter 6 is passed through pump I9 and line 2U to the pressure reduction valve 2I. The pressure is now to be released on the propane so that the evaporation of propane will produce a suiciently low temperature in the remaining solution to permit a satisfactory dewaxing operation. The propane solugoes through line 22into heat exchanger 23, where it gives up heat to the oil discharged from the centrifuge 29, valves 22 and 32 being open and r valve 31 in by pass 31 being closed. 'Ihe pressure reduction valve 2i may be placed before or after interchanger 23. The propane mixture leaving interchanger 23 passes through line 24 into cooling chamber 25, where suiiicient propane is evaporated at a suitable pressure to wit, zero pounds gauge to produce the desired temperature to Wit, F. in the remaining material. The propane carried to this point'in the system thus acts as a direct refrigerant, thus eliminating the use of expansion coils or other indirect cooling apparatus. The cooled mixture in the bottom of cooling chamber 25, consisting of a propane solution of lubricating oil and precipitated amorphous wax, issent through line 26 to pump 21 and then through line 28 to the gas tight centrifuge 29. f

The wax is discharged from the centrifuge through line 30. This wax may be worked up in any desired manner to recover propane, oil and wax.

The dewaxed oil solution is discharged from the centrifuge through line 3| and is passed through interchanger 23 in order to pick up heat from the propane solution going into the cooling chamber as described above. Leaving interchanger 23, the dewaxed solution then passes through line 32 into heater 33 which may be any type of heating equipment, such as a pipe still or heat interchanger. The heated solution .from heater 33 is passed into evaporating column 34, into which steam via 34' is introduced for the purpose of aiding the flashing of the last of the propane and reducing the remaining oil to satisfactory flash and re specifications.

The bottoms from evaporator 34 are drawn off through line 35 and sent to dewaxed lubricating oil stock storage tank 35.

The overhead from evaporator 34 is passed through line 36 to cooler 36 and into separator Condensed light lubricating oil is withdrawn through 38' and water from 38". The uncondensed propane in separator 38 is passed through line 39 to propane compressor 40 and then through line 4I, T 42, line 43, T 44, and line to cooler 46 where the compressed propane is liquefied and passes into propane storage 41.

The overhead from cooling chamber 25, consisting of propane vapors is passed through line 48 to propane compressor 49, from which it passes through T 42, line 43,`T 44, and line 45, to cooler 43 where it is condensed and passes into propane storage 41.

If the oil to be treated is an asphaltic base oil free of Wax, the oil may be sent via bypass 31, va1ve-31 being opened and valves 22 and 32' being closed, directly to heater 33 and processed as above.

The above treatment separates substantially all the oil from the bitumens forming the asphalt and also separates substantially all of the wax, if the oil contains wax,.from the bitumen.

The above description is merely illustrative of the invention and is not to be understood as limiting. Many variations will appear to those skilled in the art within the scope of my invention which I claim to be:

l. A method of separating wax from waxy oil which comprises commingling the oil and a liqueed hydrocarbon diluent consisting largely of propane under pressure suicient to prevent substantial evaporation of the diluent, passing said oil and diluent mixture through a heat exchange apparatus to a vaporizing chamber, evaporating a portion of the diluent in said chamber to materially reduce the temperature of said oil I diluent mixture and precipitate wax, separating the wax from the oil diluent mixture at said low temperature, and passing said oil diluent mixture through said heat exchange to reduce the temperature of the incoming Wax oil mixture passing to said evaporator.

2. A method of separating Wax from waxy oil comprising commingling the Wax-containing oil and a liqueed hydrocarbon diluent consisting largely of propane under pressure suflicient to prevent substantial volatilization of the diluent, in then cooling said mixture to precipitate the Wax, in separating the wax from the diluted oil and in passing the oil diluent mixture in heat exchange relationship with the incoming Wax oil mixture to cool the same.

3. A process for separating wax from waxy oil which includes the steps of compressing a refrigerant hydrocarbon gas having a vapor pressure less than that of ethane and greater than that of butane, cooling said compressed gas to cause liquefaction thereof, mixing the liqueed gas with a waxy oil, permitting said gas to expand in direct contact with said waxy oil, recycling the refrigerant gas, withdrawing the chilled waxy oil, separating wax from said chilled oil and passing said chilled dewaxed oil in heat exchange relation with the incoming waxy oil.

4. A method for separating wax from waxy oil which comprises commingling the waxy oil with a normally gaseous liquid hydrocarbon solventv having a Vapor pressure lower than that of ethane and at least as great as thatof butane under pressure sufiicient to prevent substantial evaporation of the solvent, passing the mixture in a flowing stream under substantially said aforementioned pressure and cooling the mixture in said passage, reducing the pressureon said mixture and Vaporizing a portion of the solvent to chill the oil and precipitate wax .and separatingthe` precipitated -wax from the oil and residual 5011]@1111` 15. Al method for separatingwax-.from waxy-'oil which f comprises commingling `the waxy 'oil fwith a normally "gaseous liqueed hydrocarbon solvent:

having alfvapor pressure lower"j than` that' of.

ethane-and at least as high as that!ofi-butane` under pressure, cooling the mixture in one stage by indirect heat exchange and cooling `the mixture in a second stage to precipitate wax by reducing the pressure to evaporate a portion of the solvent, separating precipitated wax from the oilsolvent mixture and passing the dewaxed oil and butane under pressure sufficient to prevent substantial evaporation of the solvent, passing said oil and solvent mixture through a heatexchanger into a chill chamber, reducing the pressure on said mixture in said passage to said chill chamber and vaporizing a portion of the solvent in said vaporizing chamber to chill the oil andprecipitate wax, separating the precipitated wax from the oil and residual solvent and passing said Wax free oil and residual solvent through said heat exchanger to reduce the temperature of the incoming wax-oil mixture passing to said chill chamber.

'7. A method; for separating wax from waxy oil which comprises commingling the wax containing oil and a liquefied normally gaseous hydrocarbon solvent having a vapor pressure `lower than that of ethane and at least as high as that of butane under pressure sufficient to prevent substantial evaporation of the solvent, passing said oil and solvent mixture through a heat exchanger under pressure, then passing said mixture to a chill chamber, reducing the pressure on said mixture in said chamberto evaporate a portion of the solvent to chill the oil and precipitate wax, separating the precipitated wax from the oil and residual solvent and passing said waxfree oil and residual solvent through said heat exchanger to reduce the temperature of the mixture of waxy oil and solvent passing through said heat exchanger to said chill chamber.

8. A method for separating wax from waxy oil which comprises commingling the wax containing oil and a normally gaseous liquefied hydrocarbon solvent having a vapor pressure lower `than that of ethane and at least as high as that of butane under pressure suiiicient to prevent substantial evaporation of the solvent, partially reducing the pressure on said solvent mixture and then passing said mixture through a heat exchanger to a chill chamber, further reducing the pressure in said chamber to evaporate a portion of the solvent to chill the oil and precipitate wax, separating the precipitated wax from the oil and residual solvent and passing the waxfree oil and residual solvent through said heat exchanger to reduce the temperature of the waxoil mixture passing to said chill chamber.

9. The method of separating wax from roil which comprises mixing a light low boiling nonviscous hydrocarbon liquid diluent consisting chiefly of propane with the wax-bearing oil,

f ashing said `mixture in a chilling chamberl whereby a portion of said hydrocarbon is removed gling with said` oil alight normally gaseous hy-' drocarbon liquid diluent having vapor pressure less than that of ethane and at least as great asthat of butane, rapidly expanding the mixture in a chilling chamber whereby a portion of the hydrocarbon diluent is evaporated to effect cooling of the diluted oil to solidify the wax in form separable from the remaining solution while leaving a solution of `oilin diluent, and mechanically separating the wax from the diluted oil.

11. A method according to claim 10 wherein the diluent consists chiefly of propane.

12. The method of continuously removing wax from petroleum oils which comprises continuously mixing an oil with a liquefied light hydrocarbon diluent having a vapor pressure lower than that of ethane and higher than that of butane,` continuously introducing said mixture into a" chilling chamber, continuously removing vapors `from said chilling chamber whereby the mixture is refrigerated and wax crystals are formed, and continuously separating the oil from the wax crystals.

13. The method of continuously removing wax from petroleum oils which comprises continuously mixing wax and oil with a liqueed light hydrocarbon diluent having a vapor pressure i lower than that of ethane and higher than that of butane, continuously introducing said mixture into a chilling chamber, continuously refrigerat- `ingthe mixture in said chamber whereby wax crystals are formed, and continuously separating the oil from the wax crystals.

14. A methodfor continuously removing wax from wax-bearing petroleum oils which comprises continuously commingling the waxy oils with a liqueiied light hydrocarbon diluent having an average constitution of more than two `carbon atoms per molecule and less than 5 c arbon atoms per molecule, passing said mixture into chilling means, evaporating a portion of the diluent in said chilling means whereby the mixture is chilled and wax is solidified while retaining sufficient diluent for separation of 'the wax from the diluted oil, and continuously separating said solidied wax from said diluted oil.

15. A method according to claim 14 wherein the hydrocarbon diluent is chieily propane.

16. A method for the separation of wax from wax-bearing petroleum oils which comprises commingling the wax-bearing oil with a liquefied normally gaseous hydrocarbon diluent having a boiling point substantially higher than that of ethaneand at least as low as that of butane in quantities suficient toI thin the oil and permit solidiiication of Wax in separable form, passing the mixture through a cooling zone to effect one cooling stage, then passing the mixture through a second cooling zone to effect a second cooling stage, to chill the oiland solidify the wax in separable form, one of the cooling stages being `effected by rapid reduction of pressure upon the mixture to effect vaporization, and separating the diluent mixture by indirect heat exchange while maintaining said mixture under pressure sufficient to maintain the diluent principally in liquid form, then releasing the pressure on the cooled waxy oil-diluent mixture sufiicient to coolthe mixture to a temperature lower than that obtained in the iirst mentioned cooling stage and low enough to precipitate Wax, maintaining sufficient of the liquefied hydrocarbon diluent in liquid formato dilute the oil and precipitated wax mixture and aid subsequent Wax separation, separating the precipitated Wax from the oil and diluent mixture, and circulating the cold dewaxed oil and diluent mixture in said indirect heat exchange to effect said rst mentioned cooling stage of the waxy oil and diluent mixture.

ULRIC B. BRAY.

CERTIFICATE CF CORRECTION. Patent No; 2,218', 55. october 22, IQLIC.

ULRIC B. BRAY.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, second column, lines 29 and A5,. claims' l and 2 respectively, for the word "'largely" -read chiefly; and thetthe said Letters Patent shouldbe-read with this correction therein that the same may conform to the record of p the case in the Patent Office.

signed and sealed this 25th day of March, A. I). 19in.

Henry Van Arsdale, (Seal) Acting Commissioner of Patents. 

